1. Field of the Invention
The present invention relates to oil well blowout preventers, and in particular to an automatic blowout preventer located within the drill stem and comprised of a slidable tubular member located between the drill pipe and drill casing which, when impacted by a blowout within the drill stem would force the slidable member upward so that its expandable end would engage with a fixed flanged collar section and would expand to fill the gap between the drill pipe and drill casing to interrupt the flow of the blowout within the drill stem.
2. General Background and Prior Art
In the field of oil and gas drilling, the most feared and dreaded occurrence would be that in the middle of a drilling for oil and gas that a blowout occur within the drill stem, creating an extreme pressure surge at the blowout upward through the drill stem and would eventually erupt through the drill floor, in most cases resulting in extreme damage to the entire drill rig assembly, and very often resulting in injury and death to workers on the drill platform, and in effect causing a shut down of the entire rig and the loss of valuable time, money and man hours.
Numerous devices have been installed within the drill assembly mechanism to assist in helping to prevent or to short circuit a blowout. However, it is recognized in the art that the most successful blowout preventer would be one which acted while the blowout is still confined within the drill stem, so that the pressure of the blowout would not have an impact upon the drill assembly above ground.
These problems are discussed in my prior co-pending patent application U.S. Ser. No. 92,573 filed Nov. 8, 1979 and incorporated herein by reference.